The fact that the kidney receives 25 percent of the cardiac output and has specialized concentrating and transporting abilities makes it unique in its susceptibility to chemical-induced toxicity. Halogenated hydrocarbons (HH) are a large group of chemicals known to produce nephrotoxicity. Because HHs are used widely as drugs, pesticides and herbicides, humans and animals are constantly exposed to these environmental pollutants. While several studies have related the metabolism of HHs to their toxicity in vivo and have superficially characterized the renal damage, they have not addressed the cellular mechanism(s) of toxicity. The main objective of the proposed research is to determine how the nephrotoxic metabolites of two model HH (hexachlorobutadiene and bromobenzene) alter proximal tubular cellular physiology to produce toxicity. Since studies from this laboratory have shown that kidney proximal tubular mitochondria are one of the earliest intracellular targets of toxicity, this project will concentrate on determining the mechanism by which these compounds produce mitochondrial dysfunction. Using a well-defined suspension of rabbit renal proximal tubules and isolated mitochondria, experiments are designed 1) to determine the relative role of mono- and di-substituted glutathione conjugates of 2-bromohydroquinone (BHQ) in producing toxicity (mitochondrial) and relate their metabolism to cysteine, BHQ and the cysteine conjugates of BHQ at the organelle (mitochondria) level; 3) to determine whether these compounds cause mitochondrial dysfunction by alkylating or oxidizing the site of toxicity; 4) to identify the "reactive species" and the amino acids altered by these compounds; and 5) to determine the subcellular site(s) of bioactivation of these compounds. By understanding how these chemicals induce toxicity, it may be possible to 1) alter their structure to maintain their usefulness but not their toxicity, 2) develop antidotal treatments, and 3) gain a better understanding of normal cellular function.